Historically utility consumption meter reading, such as for water, gas, or electricity, has been accomplished manually by human meter readers who traveled to the customers' premises. The relatively recent advances in this area include collection of data by telephone lines, radio transmission, walk-by, or drive-by reading systems using radio communications between the meters and the meter reading devices. The wireless meter reading systems make it possible to selectively obtain individual metering data with few personnel, and can increase reliability and technical accuracy.
Utility meters are equipped with at least a meter sensor unit, a transmitter, and an antenna. The meter sensor unit typically includes encoder circuitry coupled to the meter device to process and store the meter data. Multiple sensors or sensor systems may also be employed to identify and process data relating to tamper detection, power outages, temperature monitoring, and the like. An automatic utility meter reading (AMR) system also comprises a reader and a translator interfaced to the meter, where the translator obtains consumption readings from the meter and sends them to a reader via an RF signal or an electromagnetic field (EMF).
Wireless data gathering from meters located within subsurface meter pits (“pits”) presents particular challenges. These pits provide housings for protection from environmental factors, provide access to underground water lines, gas lines, etc., and so forth. Typically pit housings are constructed from various concrete and metal materials that present transmission problems. Since the meters are often positioned at the bottom of the pits, it is difficult to achieve optimal or even acceptable RF transmission out of the pit.
In water meters, the translator and meter are sealed within the pit enclosure; however, creating an effective seal in the pit enclosure can interfere with the ability of the translator's effective transmission. In a typical pit system, where the translator is located directly underneath the pit lid or there is no translator, the RF signal from the translator or meter is attenuated by as much as 30dB and, to overcome this interference, the translator or meter must operate at a higher transmission power which increases the cost of the system, wastes energy, and quickly drains batteries in battery-powered systems. In meter systems where a cable connects the meter to the translator, the system within the pit is prone to leakage problems. If the cable is damaged, water may damage the connection between the meter and the translator, allowing faulty data to be conveyed to the reader, or may totally disable the translator.
Utility meter modules are usually located in pits having a lid, with a transmission antenna that is mounted over or through the pit lid and is connected to the other module components through a hole in the lid. Connectivity of the various components through a pit lid requires special designs, and the more complex the housing structure becomes the more costly the units will be. The protruding antennas can also be damaged by vehicles and other external forces such as curious people. Another problem is that the utility meter module components become exposed and vulnerable to potential tampering and/or environmental damage once the pit lid is removed. In general, the existing remote utility meter reading systems suffer from signal attenuation, pit leakage, and battery drainage among other problems